The invention relates generally to a wound electrical capacitor, particularly power capacitors, which include within the housing a structure adapted to rupture in the presence of an excessive pressure in the housing and thereby interrupt the electric supply to open the capacitor circuit.
In oil-impregnated power capacitors, particularly capacitors having electrodes formed by regeneratable coatings, and which are impregnated with oil, gaseous decomposition products are often formed during operation as a result of the self-healing processes, which decomposition products can produce a strong pressure increase in the interior of the housing. To avoid possible explosion of the housing under such strong pressure increase, which also can occur at the end of the life expectancy of the capacitor, excess-pressure break-away or interruption protective devices or fuses are commonly employed in such capacitors, which are operative to open the capacitor circuit in the presence of a large internal pressure increase.
Such a structure is disclosed, for example, in German LP No. 975,024, which illustrates a circuit opening arrangement for capacitors which is disposed in the housing and is connected, by soldering, into the wiring as a separate component. A suitable break-away strip is supported between two plates of insulating material and tensioned by means of suitable tensioning members, with the break-away strip possessing a predetermined rated breaking point.
It is also known to employ a break-away wire which possesses a rated breaking point, as the circuit-opening device. However, such a break-away wire is not suitable for employment in power capacitors.